The present invention relates to an equipment for cold-drawing a metal wire.
Drawing, i.e., the section decrease of a metal wire or another metal object through drawing dies, is obtained by pulling the material through the drawing die by means of drawing machines.
A commonly used technique, especially for metal wires with a round section, allows a drawing of a metal wire to be obtained by subsequent section decreases due to the passage of the wire in drawing dies placed one after the other and contained, along with a holding tank of the lubricant for the wire, in a single drawing apparatus. The lubrication is obtained by means of the interposition of the lubricant between the metal wire and the drawing die due to both the motion of the wire towards the drawing die and the geometric contour of the drawing die itself.
A piece of equipment for cold-drawing a metal wire is described in patent EP 1554062. The equipment comprises a sequence of a sleeve with cylindrical hole and a drawing die with conical hole. The sleeve is inserted into a support and ends with an extension fitted in said conical hole of the drawing die. The support has a first annular projection and the drawing die has a second annular projection coupled to said first projection so as to keep the sleeve and the drawing die in place.
With said equipment, the operation of assembling the drawing die onto the sleeve becomes very easy; however, problems of adhesion of the lubricant to the wire to be drawn occurred with said equipment, especially at low drawing rates, e.g., in the case of few meters per second.